eNate
Posts: 641
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Re: Questions from a new 2016 owner

Mon Jul 20, 2020 9:30 am

So Andre, the unknown that any of us can only guess at is the size of your rear wheels.

You can either:
a. dismount a rear wheel and look at the dimensions imprinted on the inside
b. measure width as best able -- it's only 1/2" difference so you'll need to measure carefully
c. look through the spokes at where the wheel bolts to the rotor and see if you notice a difference between the front and rear

Unfortunately, there are no telltale indicators I'm aware of on the exterior of the wheel.

Will a 175 tire work on a 5.5" rear? Yes.

Will a 175 tire work on a 5.0" rear? The tire will mount safely (they are compatible by industry standards), but I don't know if you'll have enough clearance between the inner sidewall and the fender wall. I would check this by taking something 10mm thick (find a fat pen, or a socket, or a lego) and reach behind the tire to slide it through this gap. If there are no clearance issues, a 175mm tire will most likely work fine here on a 5.0 +43ET stock rim.
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jadnashuanh
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Location: Nashua, NH USA

Re: Questions from a new 2016 owner

Mon Jul 20, 2020 1:13 pm

Putting the wider tire on the 5" rim will cause it to crown a little more meaning without playing with the air pressure, you'll get uneven wear. Lowering the air pressure to let it ride flatter will decrease your range. These are slight changes, but measurable.

Depending on how old the winter tires are (you can tell from the marking on the sidewall, but may need a decoder), and how worn they are, I might just run them until they need to be replaced. The rubber in tires continuously hardens as they age, and the industry recommendation is to trash any that are more than 5-years old, regardless of wear. As they harden, they start to lose grip which can be a factor in acceleration and braking as well as cornering. If they aren't too old and have decent tread, I'd seriously look for a take-off set from maybe a recycler and use them, saving the winter tires for when it's colder (if it gets that way where you live). From a safety standpoint, the square set is fine. On a rear-wheel drive vehicle, the rears do wear out faster. But, an advantage of a square setup is that you can rotate them which is not possible with the wider rear wheels. This will help maximize their life.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

eNate
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Re: Questions from a new 2016 owner

Mon Jul 20, 2020 3:33 pm

For what it's worth, Jim, the 155 is the minimum tread width recommended for a 5.0" wheel. 165 or 175 is preferred. 185 is max.

A 5.5" wheel, on the other hand, goes 165 minimum, 175-185 preferred, 195 maximum.

I recall coming across an SAE table with these figures, but can't find it, so this link will have to suffice: https://www.tiresandco.ca/tire-equivalence-advice.html

Now I imagine BMW maybe found running minimum tread width maximizes efficiency, but if that's the case, why did they chose the rear combination that they did, rather than a 6.0 wheel, or 165 tread.

But in any case, I don't want anybody reading this thread to leave thinking 175 tires on 5.0 rims is unsafe or compromised.
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eCharles
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Re: Questions from a new 2016 owner

Tue Jul 21, 2020 10:30 am

I see that BMW recommends premium gas for the REX models, but is this necessary?

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MKH
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Location: Dallas

Re: Questions from a new 2016 owner

Tue Jul 21, 2020 11:50 am

I see that BMW recommends premium gas for the REX models, but is this necessary?
It's what is listed as the fuel recommended in the BMW 650 scooter - which is the REx engine. With the finicky issues some have had with the REx, I stick with Premium - why tempt fate? The extra 60 cents a tank, I'm good with :D

I remember reading a study some time back, on a test that showed that running regular gas in a car where premium was recommended actually cost more, because the lower octane gas resulted in poorer MPG.
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

eCharles
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Joined: Sat Jul 18, 2020 3:32 pm

Re: Questions from a new 2016 owner

Tue Jul 21, 2020 12:37 pm

MKH wrote:
Tue Jul 21, 2020 11:50 am
I see that BMW recommends premium gas for the REX models, but is this necessary?
It's what is listed as the fuel recommended in the BMW 650 scooter - which is the REx engine. With the finicky issues some have had with the REx, I stick with Premium - why tempt fate? The extra 60 cents a tank, I'm good with :D

I remember reading a study some time back, on a test that showed that running regular gas in a car where premium was recommended actually cost more, because the lower octane gas resulted in poorer MPG.
Good point, thanks.

jadnashuanh
Posts: 5196
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Re: Questions from a new 2016 owner

Tue Jul 21, 2020 1:55 pm

One thing that is USUALLY part of premium gas is more detergents. That is particularly important with an engine that may not be run that often. In fact, check out www.toptiergas.com for more information on this cooperative arrangement between fuel suppliers and car manufacturers. Many, but not all suppliers abide by the numerous vehicle manufacturers' recommendations. That info may help you with any ICE vehicle you own, too.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

Amsr
Posts: 4
Joined: Tue Jul 07, 2020 1:25 pm

Re: Questions from a new 2016 owner

Thu Apr 22, 2021 1:48 am

eNate wrote:
Mon Jul 20, 2020 3:33 pm
For what it's worth, Jim, the 155 is the minimum tread width recommended for a 5.0" wheel. 165 or 175 is preferred. 185 is max.

A 5.5" wheel, on the other hand, goes 165 minimum, 175-185 preferred, 195 maximum.

I recall coming across an SAE table with these figures, but can't find it, so this link will have to suffice: https://www.tiresandco.ca/tire-equivalence-advice.html

Now I imagine BMW maybe found running minimum tread width maximizes efficiency, but if that's the case, why did they chose the rear combination that they did, rather than a 6.0 wheel, or 165 tread.

But in any case, I don't want anybody reading this thread to leave thinking 175 tires on 5.0 rims is unsafe or compromised.
I have 4 5j whells size on front and rear with 155 standard tyre size. I would like to know if i can put out 175 60 19 tyres on my rear wheels.... Does anybody knows?

eNate
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Re: Questions from a new 2016 owner

Thu Apr 22, 2021 8:06 am

Amsr wrote:
Thu Apr 22, 2021 1:48 am


I have 4 5j whells size on front and rear with 155 standard tyre size. I would like to know if i can put out 175 60 19 tyres on my rear wheels.... Does anybody knows?
The 17 5 will definitely fit the 5.9 wheel.

You need to determine if the extra rubber will clear the suspension components.

When I've done this on other vehicles, I've used a socket from a ratchet set that's about the diameter on equal to the reduction in clearance as a result of the fatter tire (or wheel).

In your car the tire sidewalls will each stick out 10mm ether side. I'd find a socket that's 11 or 12mm diameter and run it along the inner sidewalks. If there a clearance that the socket can't squeeze through, that's a potential point of contact.
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Amsr
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Re: Questions from a new 2016 owner

Thu Apr 22, 2021 11:23 am

eNate wrote:
Thu Apr 22, 2021 8:06 am
Amsr wrote:
Thu Apr 22, 2021 1:48 am


I have 4 5j whells size on front and rear with 155 standard tyre size. I would like to know if i can put out 175 60 19 tyres on my rear wheels.... Does anybody knows?
The 17 5 will definitely fit the 5.9 wheel.

You need to determine if the extra rubber will clear the suspension components.

When I've done this on other vehicles, I've used a socket from a ratchet set that's about the diameter on equal to the reduction in clearance as a result of the fatter tire (or wheel).

In your car the tire sidewalls will each stick out 10mm ether side. I'd find a socket that's 11 or 12mm diameter and run it along the inner sidewalks. If there a clearance that the socket can't squeeze through, that's a potential point of contact.
Thanks, so 1cm more on each side with the 5j wheels specific offset using 175 60 19. The offset on the 5,5j wheels is higher than the 5j value, so my rear tyre will be more apart from the center of the car than if using the 5,5j? Or does the offset is diferent due the diferent wheel size 5j vs ,5j?

Regards

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